In general, a microphone is a device used to convert a sound into an electrical signal. The microphone is applicable to various communication devices such as a mobile communication device such as a terminal, an ear phone, or a hearing aid. Such a microphone requires excellent sound performance, reliability, and operability.
A capacitive microphone based on Micro-Electro-Mechanical Systems (MEMS) technology (hereinafter referred to as ‘MEMS microphone’) represents excellent sound performance, reliability, and operability compared to a conventional Electret Condenser Microphone (hereinafter referred to as ‘ECM microphone’)
Such MEMS microphones are classified into non-directional (all directions) microphones and directional microphones, according to a directional characteristic.
A non-directional microphone is a microphone having the same sensitivity in all directions with respect to an incident sound wave. A directional microphone is a microphone where sensitivity is changed according to a direction of an incident sound wave. Directional microphones are further classified into single directional microphones and bi-directional microphones.
For example, a directional microphone is used when a recoding operation is performed in a narrow room or a user receives only desired sound in a room with reverberation.
When a microphone as described above is applied to a vehicle, since a sound source is distant and noise is changeably generated in the vehicle environment, a microphone that is robust to variation in noise environment in the vehicle is needed. In order to implement this, a directional MEMS microphone for receiving a sound source in only a desired direction can be applied.
Since a directional microphone, according to the related art as described above, may receive a sound source in only the desired direction, the directional microphone is advantageous to be robust to a noise input from a peripheral portion. However, a directional microphone has lower sensitivity than that of a non-directional microphone, and the frequency response characteristic is not excellent.
The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.